1. Field of the Invention
The present invention relates to a correction method of luminance unevenness in an image display apparatus.
2. Description of the Related Art
A liquid crystal display apparatus (LCD), a plasma display apparatus (PDP), a field emission type display apparatus (FED), an organic EL display apparatus (OLED), and so on are available as flat screen display apparatuses (FPDs).
With this type of flat screen display apparatus, a large number of display elements must be formed on a substrate. Characteristics of the display elements are affected by slight differences in manufacturing conditions and the like. Therefore, it is typically difficult to make the characteristics of all of the display elements included in the FPD perfectly uniform. Non-uniformity in the display characteristics causes luminance variation (luminance unevenness) on the display apparatus, leading to deterioration in image quality.
For example, in an FED, electron-emitting devices of surface emission type, Spindt type, MIM type, and carbon nanotube type are used as display elements. When a shape or the like of an electron-emitting device varies due to differences in the manufacturing conditions of the electron-emitting device and so on, the electron emission characteristic of the electron-emitting device also varies. As a result, luminance unevenness occurs on the FED, leading to a deterioration of the image quality.
In constitution proposed in response to this problem, an image signal (luminance data) is corrected in accordance with a light emission characteristic of each display element.
For example, a constitution in which correction value tables are provided for all gradations of the display elements has been proposed (see Japanese Patent Application Laid-open No. 2000-122598). However, when this constitution is employed, the volume of the required correction value tables increases as the number of display elements and the number of gradations increase. Further, large increases occur in the amount of time required for measurements and calculations used to determine the correction value tables. Hence, there is demand for a method with which the volume of the correction value tables can be reduced (leading to reductions in cost and difficulty) and accurate correction values can be determined in a short amount of time.
A conventional technique relating to this problem is disclosed in the specification of U.S. Pat. No. 6,097,356, for example. More specifically, in the constitution disclosed in the specification of U.S. Pat. No. 6,097,356, a correction value table is provided only in relation to a specific gradation instead of providing correction value tables for all gradations. Correction values for gradations not provided with a correction value table are then obtained by interpolating the correction value table using a linear function or a higher order function.
In another proposed constitution (see Japanese Patent Application Laid-open No. 2006-047510), luminance unevenness caused by differences in the resistance and the capacitance of scanning wirings and modulation wirings is reduced by providing correction data for correcting the differences in the resistance and capacitance of the scanning wirings and modulation wirings.